This invention relates to apparatus for preventing the progressive spread of fire by the progressive burning of a plastic article or assembly such as a pipe or conduit system and more particularly to apparatus which is adapted to seal the walls of a plastic pipe system to interrupt and baffle it when it softens in the presence of fire and before it ignites, to insure against the progressive burning of the pipe system through a fire-resistant wall, floor or partition.
With the increasing use of plastic pipes or conduits in buildings, many devices have been developed to seal off openings through which such pipes and conduits extend. One example of such a device is described and illustrated in U.S. Pat. No. 4,894,966, entitled Fire Stopping Apparatus. While the device described therein is practical for new conduit installations, it is not practically installable on existing conduit systems.
With the introduction of more stringent fire safety standards and the desire to install Fire Stopping Apparatus on existing conduit systems, a need has evolved for a Fire Stopping Apparatus which can be used on existing conduit systems.